An MD2-perturbing peptide has therapeutic effects in rodent and rhesus monkey models of stroke

Abstract

Studies have failed to translate more than 1000 experimental treatments from bench to bedside, leaving stroke as the second leading cause of death in the world. Thrombolysis within 4.5 hours is the recommended therapy for stroke and cannot be performed until neuroimaging is used to distinguish ischemic stroke from hemorrhagic stroke. Therefore, finding a common and critical therapeutic target for both ischemic and hemorrhagic stroke is appealing. Here, we report that the expression of myeloid differentiation protein 2 (MD2), which is traditionally regarded to be expressed only in microglia in the normal brain, was markedly increased in cortical neurons after stroke. We synthesized a small peptide, Trans-trans-activating (Tat)–cold-inducible RNA binding protein (Tat-CIRP), which perturbed the function of MD2 and strongly protected neurons against excitotoxic injury in vitro. In addition, systemic administration of Tat-CIRP or genetic deletion of MD2 induced robust neuroprotection against ischemic and hemorrhagic stroke in mice. Tat-CIRP reduced the brain infarct volume and preserved neurological function in rhesus monkeys 30 days after ischemic stroke. Tat-CIRP efficiently crossed the blood-brain barrier and showed a wide therapeutic index for stroke because no toxicity was detected when high doses were administered to the mice. Furthermore, we demonstrated that MD2 elicited neuronal apoptosis and necroptosis via a TLR4-independent, Sam68-related cascade. In summary, Tat-CIRP provides robust neuroprotection against stroke in rodents and gyrencephalic nonhuman primates. Further efforts should be made to translate these findings to treat both ischemic and hemorrhagic stroke in patients.

The Absence of Extracellular Cold-Inducible RNA-Binding Protein (eCIRP) Promotes Pro-Angiogenic Microenvironmental Conditions and Angiogenesis in Muscle Tissue Ischemia

“…Recently, a protective effect in ischemic stroke was reported for an eCIRP-derived peptide, which interferes with eCIRP s binding ability to the MD2 receptor, resulting in a significant reduction of the ischemic infarct area as well as the inhibition of apoptosis and necroptosis in murine and rhesus monkey models [99]. This experimental approach highlights an important milestone in designing CIRP-related therapeutic treatments for ischemia-related pathologies.…”

Neuronal MD2 Induces Long-term Mental Impairments in Septic Mice by Facilitating Necroptosis and Apoptosis

“…MD2 synchronously mediated apoptosis and necroptosis, and excitatory neuronal MD2 deletion relieved depression-like behaviors in the septic mice Given the current unsatisfactory treatments, we attempted to identify a target that affects both apoptosis and necroptosis. MD2 is an essential cofactor protein of TLR4 that participates in the in ammatory response and is a key mediator of apoptosis and necroptosis in stroke models [10]. Here, we explored the expression of MD2 in neurons in the hippocampus of the septic mice.…”

“…4A, B, C, D). To further con rm the crucial role of MD2 in the pathology of SAE, we constructed transgenic mice that with speci c MD2 knockout in excitatory neurons (see our previous research for details [10]). The expression of apoptosis-and necroptosisassociated proteins was reduced in the hippocampus of the CaMKII-MD2 / mice compared with their littermates (Fig.…”

“…According to the high a nity between the cold-inducible RNA binding protein CIRP and MD2 [11], we synthesized a blocking peptide to mimic the 106-125 domain of CIRP and link the trans-trans-activating (Tat) transmembrane functional domain (YGRKKRRQRRR) to form Tat-CIRP (YGRKKRRQRRR-GRGFSRGGGD RGYGG), which promotes penetration of the BBB. For other details, see our previous study [10].…”

“…Therefore, elucidating the underlying mechanism of apoptosis and necroptosis in neuronal loss in SAE may lead to treatments for long-term depression in patients with this condition. Our previous study con rmed that myeloid differentiation factor 2 (MD2) is the crosstalk mediator of various PCDs and that inhibition of MD2 effectively reduced stroke injury [10]. Nevertheless, the role of MD2 in the pathology of SAE has not been demonstrated.…”